1. Field of the Invention
The invention relates generally to an apparatus and method for detecting tampering. More particularly, the present invention relates to an apparatus and method for detecting tampering of a printer compartment.
2. Description of the Related Art
Most types of printers have compartments in which printer contents may be contained. For example, a printer may have a compartment in which printer paper is contained. In another example, a printer may have a compartment that contains circuitry, such as a processor.
In some cases, a printer compartment may contain sensitive contents. In these cases, one may desire to prevent someone from tampering with the sensitive contents. Tampering is any contact with an object or data that is considered undesirable by at least one party, such as a government, individual, or some other entity.
For example, some countries enforce fiscal laws that require retailers to keep special records of their transaction data using fiscal printers. A fiscal printer is a type of printer that is used at a point of sale to facilitate a transaction. A fiscal printer uses an existing single or double station printer platform and adds logic that complies with a government's law. This logic may contain data records of transactions involving the fiscal printer. The logic is contained in a printer drawer that slides into the printer beneath the existing printer platform.
The fiscal printer, and in particular the printer drawer containing the logic, may need to meet tamper-proof requirements set by a particular government. For example, a law may require that a “tamper” state be evident if the printer drawer containing the logic is pulled out of the printer by more than a threshold distance. The law may also require that a printer be unable to operate until a government agent resets the printer.
One current method for tamper proofing the printer drawer uses a special screw to prevent the drawer from being pulled out of the printer. The special screw is sealed such that the seal is broken if the drawer is pulled out of the printer. However, this method requires that a special technician replace the seal after the seal is broken, thereby increasing the cost and labor required to implement this method. Also, one can detect whether the drawer has been tampered with only by visual inspection.
Another current method for tamper proofing the contents of the printer drawer embeds the printed circuit boards containing the logic in epoxy. For example, these printed circuit boards may be a fiscal memory and an electronic journal. However, in this method, visible inspection is required to determine whether an attempt has been made to tamper with the printed circuit boards. Furthermore, in the event that a tamper has occurred, a special technician may be needed to restore the circuitry to an original state.
Another current method for tamper proofing the contents of the printer drawer places a physical cover, such as a plastic box, over the electrically programmable read-only memory that is used in the logic. For example, the electrically programmable read-only memory may contain code that manages the operation of the printer. However, as in the other current methods, visible inspection is required to determine whether an attempt has been made to tamper with the electrically programmable read-only memory. Also, in the event that a tamper has occurred, a special technician may be needed to restore the circuitry to an original state, such as by replacing the physical cover.